This invention relates to recirculating ball nut and screw or splined shaft assemblies which comprise an externally grooved, ball-accommodating shaft with a complementally internally grooved nut having a circuit for precision bearing balls which recirculate in the grooved parts. More particularly, it is concerned with methods of providing bearing ends for the shafts of such assemblies, with some of the bearing ends incorporating a drive attachment or coupling configuration. The invention is further concerned with the products formed by practicing the method.
Previously, bearing surfaces and drive configuration surfaces of the required diameter and type have been machined on demand, and to specification, on the ends of the grooved shaft at the time of machining the shaft in the factory, and the assemblies have been then marketed in finished form. Some time has been required to prepare the drawings or specifications necessary to place such orders, schedule them in the factory for production, produce them, and ship them.
One of the prime objects of the present invention is to provide a method which permits the customer, or the customer's assembler, to more quickly provide the required end configurations for various diameter grooved shafts of the desired length. The concept envisions the production of pre-machined ends at the factory in a variety of standard sizes and configurations which can be inventoried and ordered to suit the particular length of grooved shaft to be used with a given ball nut. The method of fabricating to be described dramatically shortens the time required for the production of a recirculating ball nut and screw assembly from days to hours.
Still another object of the invention is to provide a method of making a ball nut and screw assembly, having finish-machined driver or bearing ends of the required size and configuration, which can be performed by customers with no access to precision turning or grinding machinery to provide the particular shaft ends which are required for a particular ball nut and screw assembly to function.
A further object of the invention is to provide a very economical method of fabricating ball nut and screw or splined shaft assemblies which can be performed on site by relatively unskilled work crews using only very simple and readily available hardware.
Still another object of the invention is to provide a method for forming a recirculating ball nut and screw or splined shaft assembly of the character described which provides an assembly with the required precision without undue expense and with reliability.
A still further object of the invention is to provide an assembly of the character defined which operates with efficiency, and which has a predictable service life and requires little or no maintenance.
Applicant is aware of the following listed patents which applicant incorporates herein by reference but points out that none of them, either alone or in combination, suggest the novel method and product which applicant has claimed.
______________________________________ 3,546,930 Flarsheim 3,656,358 Kopp 4,905,533 Benton et al 4,938,090 Brusasco Canadian 671,403 ______________________________________
None of these patents suggest the pre-machining of separate attachment end components in standard configurations to provide the external bearing surfaces and drive attachment configurations which particular size ball screws require for the functions to be performed and the loads which they are to bear.
Other objects and advantages of the invention will be pointed out specifically or will become apparent from the following description when it is considered in conjunction with the appended claims and the accompanying drawings.